CHAIN-158 — Event Grid topic without authentication

Summary

Severity: High · Likelihood: Medium · Logic: ALL

Why this chain matters

An Event Grid topic accepts events from any source (no SAS, no AAD). An attacker publishes forged events that downstream consumers trust as legitimate — common for order-confirmation systems, payment events, and audit trails.

Component rules

This chain fires when its trigger conditions are met by the following rules. Click any rule to see its detection logic and compliance mappings.

Rule ID	Role
zt_int_003	Trigger
zt_wl_002	Trigger

Attack walkthrough

Step 1 — POST a forged event to the topic endpoint.

Actor: Attacker
MITRE ATT&CK: T1584
Enabled by: zt_int_003

Attacker gain: Event delivered to subscribers.

Step 2 — Process the forged event as if it were real.

Actor: Subscriber app
MITRE ATT&CK: T1565.001
Enabled by: zt_wl_002

Attacker gain: Fraudulent business transactions processed.

Blast radius

Initial access	Public topic endpoint.
Max privilege	Event injection.
Data at risk	Business event integrity
Services at risk	Every subscriber

How the logic works

The chain fires only when every rule above has at least one finding in the current scan. Missing any one rule breaks the chain — so remediating any single step disrupts the attack path.